Domain Name System (DNS) History

Alphabetic host names were introduced on the ARPANET shortly after its creation, and greatly increased usability since alphabetic names are much easier to remember than semantically meaningless numeric addresses. Host names were also useful for development of network-aware computer programs, since they could reference a constant host name without concern about changes to the physical address due to network alterations. Of course, the infrastructure of the underlying network was still based on numeric addresses, so each site maintained a "HOSTS.TXT" file that provided a mapping between host names and network addresses in a set of simple text records that could be easily read by a person or program.

It wasn't long before people realized that keeping multiple copies of the hosts file was inefficient and error-prone. Starting with a formal proposal for centralization in Host Names On-line, RFC 606, in December, 1973, proceeding through agreement in Host Names On-Line, RFC 608, and further discussions in Comments on On-Line Host Name Service, RFC 623, it was settled by March, 1974 with On Line Hostnames Service, RFC 625, that the Stanford Research Institute Network Information Center (NIC) would serve as the official source of the master hosts file.

This centralized system worked well for about a decade, approximately 1973 to 1983. However, by the early 1980's the disadvantages of centralized management of a large amount of dynamic data were becoming apparent. The hosts file was becoming larger, the rate of change was growing as the network expanded, more hosts were downloading the entire file nightly, and there were always errors that were then propagated network-wide. Change was required, but a spark was needed.

As described in Computer Mail Meeting Notes, RFC 805, it was initially the need for a real-world solution to the complexity of email relaying that triggered the development of the domain concept. A group of ARPANET researchers, principles, and related parties held a meeting in January, 1982, to discuss a solution for email relaying. As described on the email addresses page, email was often originally sent from site to site to its destination along a path of systems, and might need to go through a half a dozen or more links that would connect at certain times of the day. For example, the following actual communication path shows individual systems separated by "!", with the destination user named "grg" tagged on at the end.